A flat mop is a mop of which the head is flat so that it may completely contact the ground surface and even may go deep into dead areas of a sofa, furniture and the like. Currently, the flat mop comprises a mop head and a mop pole. The mop head comprises a panel on which a cloth is installed. To increasingly make the mop become more effective, a double-sided mop is currently implemented. The panel of the mop head of the double-sided mop has two sides on which the pieces of cloth are installed, respectively, and the mop pole is hinged between the two pieces of cloth. To make the mop pole freely rotate up and down relative to the mop head, a corresponding slot must be formed on the panel and each of the pieces of cloth, thereby making the mop pole smoothly pass through the slots. However, the slots being formed on the panel and each of the pieces of cloth, the area of slot is hollow, which brings poor effect on floor mopping due to the slots that offers effective cleaning. Further, the panel applies a weak force to the floor, which affects the quality of cleaning.
Consequently, because of the technical defects described above, to provide the rotary valve improver, the applicant, based on many years of research and experience in the relevant industry, has developed the present invention, which may effectively improve the defects described above.